Circuit breaker



Feb. 9, 1943. T. LINDSTROM `vETAL CIRCUIT BREKER Filed July lO, 1941 vI5Sheetsl-Sheet lA .lNvENToRS Twe mds/from and Jeff-ome Sandi/2.

ATTORN wlTNEssEs:

Patented Feb. 9, 1943 UNiTED STAT 35 PTNT GFFICE CIRCUIT BREAKER TureLindstrom, Edgewood, and Jerome Sandin, Forest Hills, Pa., assignors toWestinghouse Electric & Manufacturing Company,

East

12 Claims.

The invention relates to circuit breakers of the type embodying anoperating mechanism which is manually operable to open and close thecircuit and automatically operable to open the circuit in response topredetermined conditions. The present invention constitutes animprovement over the circuit breaker mechanism disclosed in Patent2,083,304 issued to Ture Lindstrom, June 8, 1937, and assigned to theassignee of this invention.

An object of the invention is the provision of a manually andautomatically operable circuit breaker with an improved means forpreventing the holding of the circuit closed during the existence of anoverload circuit condition.

Another object of the invention is the provision of a circuit breakerwith an improved means for preventing reclosiug of the circuit byimproper manipulation of the operating handle following an automaticopening operation of the circuit breaker.

Another object of the invention is the provision of a manually andautomatically operable circuit breaker with an improved means forpreventing reclosing movement of the contacts when the handle is held inclosed position during and following an automatic opening operation ofthe breaker.

Another object of the invention is the provision of a manually andautomatically operable circuit breaker with an improved latching meansfor holding the contacts in open position after automatic openingthereof until the operating handle has been properly operated to resetand reclose the circuit breaker.

Another object of the invention is the provision of a circuit breakerwith an improved holding, or latching means as previously described andwherein the latching means is jointly controllable by the circuitbreaker operating mechanism and the handle.

Another object of the invention is the provision of a manually andautomatically operable circuit breaker with a pair of latches disposedside by side and engageable with the same element of the mechanism, oneserving to hold the contacts in full open position after automaticopening thereof until the handle is properly operated to reset andreclose the breaker and the other to hold the contacts in open positionuntil the main operating spring has been given a maximum operatingstress and at this point to release the mechanism so that the contactswill be closed quickly and positively.

Another object of the invention is the pro- Vision of a circuit breakeras previously described that is simple, compact, reliable in operation,and inexpensive to manufacture.

rI'he novel features that are considered characteristic of the inventionare set forth in particular in the appended claims, the inventionitself, however, both as to structure and operation, together withadditional objects and advantages thereof, will be best understood fromthe following detailed description of several embodiments thereof whenread in conjunction with the accompanying drawings, in which:

Figure l is a front elevational view of a threepole circuit breakerembodying the principal elements of the invention. The cover has beenpartly broken away to more clearly show some of the parts of the circuitbreaker;

Fig. 2 is a vertical sectional view of the circuit breaker takensubstantially on line II-Il of Fig. 1 and looking in the direction ofthe arrows;

Fig. 3 is an enlarged detail View, partly in section, of the circuitbreaker mechanism and the contact structure in the closed positionthereof. Some of the parts have been broken away more clearly to showthe structure;

Fig. 4 is an enlarged detail View similar to Fig. 3, showing, thebreaker mechanism and the contact structure in the tripped openposition;

Fig. 5 is an enlarged detail View similar to Fig. 3, showing the circuitbreaker mechanism and the contact structure in the manually openedposition;

Fig. 6 is an enlarged detail View similar to Fig. 3 showing the circuitbreaker mechanism and the Contact structure in the tripped open positionbut with the operating handle held in closed position;

Fig. 'l is a perspective View of the circuit breaker operating mechanismand a part of the contact structure;

Fig. 8 is a front elevational view of a part of the latching mechanism;and

Fig. 9 is a detail view of a part of the operating mechanism showing amodied form of one of the latches.

Referring to the drawings, a base l of moulded insulating material hasmounted thereon six terminals 3 and 5, a trip device l, an operatingmechanism 9 with its associated assemblage of switch members Il, the arcextinguisher i3, and three stationary Contact assemblages l5. Themovable Contact assemblages Il and the three stationary contactassemblages i5 combine to form a plurality of poles. Each of the polesis insulated from the adjacent pole by means of insulating barriers I'I(Figs. 1 and 2) moulded integral with the base I. These barriers are inalignment with similar barriers 2| in a cover I9 also made cf insulatingmaterial. An operating member 23 is provided with a handle 25 and ispivotally supported on the frame 4I of the operating mechanism 9. Asuitable opening is provided in the cover I3 for the operating handle.The trip device 'I is secured in position by screws 3| and 33 which alsoserve to connect terminals and 37 of the trip device, respectively, toflexible shunt conductors 39 and the terminals 5.

The electrical circuit for each of the poles is substantially the sameand extends from the terminal 3 through the main stationary contactassemblage I5, the cooperating movable contact assemblage II, theflexible shunt conductor 39, terminal 35, trip device 'I to the terminal5.

The assemblage of switch-members II is pivoted to the frame 4I of theoperating mechanism 9 by means of a pin 42. A metal tie-bar 43 rigidlyconnects the three switch assemblages II so that they pivot as a unitabout the pin 42. Each of the switch members I I is secured to thetie-:bar 43 by means of a clamp 45 and a bolt 4'I. In order to preventshort circuiting the several poles the switch members I I are insulatedfrom the tie-bar 43 by an insulating tube 48 surrounding the tiebar 43.

Each of the movable contact assemblages I includes a pair of contactmembers 52 supported on a pivot 53 carried by inwardly extendingprojections 55 of the clamp member 45. The contact members 52 are biasedinto engagement with contacts 56 of the stationary contact assemblage bysprings 55. Projections 6I on rearwardly extending portions 69 of thecontact members 52 are adapted to engage the projections 54 of the clampmember 45 to limit the counter-clockwise movement of the members 52about their pivot 53.

The third contact member 49 (Figs. 2, 3, 4, 5 and 6) of the movablecontact assemblage II is disposed between the outer contacts 52 andincludes an arcing contact 59, a body portion 62 provided with a slot 93(Figs. 3, 4, 5 and 6) and an intermediate contact 5 I. A rearwardlyextending portion 64 of the body 62 is pivoted on the pin 53 and isconductively joined to the central portion cf a flexible shunt conductor39. The outer portions of the shunt conductor 39 are connected to themain contact members 52. A spring 66 compressed between the top of theportion 62 and a Y projection 61 of the clamp 45 provides the contactpressure for the contacts 59 and 5I which are adapted to engagecooperating contacts of the stationary contact means I5. A spring guide68 passes through an opening in the projection 61 and has its lower endcurved to lie within the slot rotate about the common pivot 42 is denedby the engagement of a portion of the central clamp member 45 withportions 82 of the side walls of the frame 4I (see Figs. 4 and 5).

VThe arc extinguishers I3 may be of the spaced plate type and aredisposed adjacent the arc path, the plates being provided with slots ofsubstantially the same outline as the moving contacts. The arc is movedinto the spaces between the plates where it is rotated by a suitablemeans until it is cooled and extinguished. Patent 1,896,764, issued toM. W. Brainard on February 7, 1933, fully discloses and describes thestructural features and operation of an arc extinguisher of this type.

The frame 4I, which is secured to the base I by screws 99 and 9|,supports the breaker operating mechanism 9. This mechanism includespairs of toggle links 33 and 54, pivotally connected by a knee pin 94.The toggle link 83 comprises a pair of parallel links rigidly connectedby a yoke 92, and the toggle link 94 also comprises a pair of parallellinks rigidly connected by a yoke 95. The yoke of the toggle link 84 isdisposed to engage the underside of the yoke 92 of the toggle link 83 tolimit the outward motion of the knee of the toggle.

The toggle link 83 is pivotally connected by means of a pin 93 to theportion 'I5 of the central clamp member 35 and thus to the three switchmembers I I. The ends of the parallel links forming the toggle link 84are rounded as indicated at |94 (Fig. '7) to form bearings which engagesuitable recesses in the upwardly extending arms of a bell crank carrier|95 which is pivoted at its apex to the frame 4I by means of a pin |99.Retainer plates |96 (only one being shown) are secured to the outerfaces of the bell crank lever |95 to prevent lateral displacement of thetoggle link 84. These plates |96 are provided with openings into whichproject studs I9? 'in the bearing portions |94 of the toggle links 84 toprevent longitudinal displacement of the bearings from the bell crank|95. An overcenter spring 99 is tensioned between the knee pin 94 of thetoggle and the operating member 23, the spring being threaded at one endonto a member 9'I which is pivotally connected to the member 23 by a pin|99. At its opposite end, the spring 99 is threaded onto a member 98pivoted on the knee pin 94 of the operating toggle. The spring 99 at alltimes exerts a tension force between the knee of the toggle 83-34 andthe operating member 23.

The bell crank carrier lever |95 comprises a pair of parallel bellcranks |95 joined at their left hand ends (Fig. 3) by a cross bar oryoke |98. A latch member III comprising a pair of substantially parallelmembers pivoted to the frame 4I by means of a pin ||5 has a yoke |I2joining the two members substantially above the pivot pin ||5. In thenormal position of the parts, the yoke I I2 lies directly above and inthe path of travel of the yoke I 98 thus normally preventing clockwisetravel of the bell crank carrier |95 under the inuence of the spring 99.The latch member III is releasably retained in its normal latchingposition by a latch II 4 of the trip device 'I and is provided with alatch engaging element II'I pivotally mounted on a yoke II3 joining thefree ends of the latch members III.

The latch member I I is normally restrained in latching position by thetrip device I which is responsive to predetermined overload conditionsin the circuit of any of the poles of the breaker to release the memberIII and thereby cause automatic opening of the circuit breaker. Theinstant invention is not particularly concerned with the details of thetrip device I as any suitable device possessing the propercharacteristics may be used, for instance, a trip device such as isdisclosed in United States Patent 2,043,306, granted June 9, 1936 toJerome Sandin and which is assigned to the assignee of the instantinvention. Such a trip device includes a current responsive bimetal tripelement and an electromagnetically responsive trip element electricallyconnected in each pole of the breaker, and a common trip bar operable byany one of the thermally or magnetically responsive trip elements toeiTect release of the circuit breaker latching lever` III.

Upon the occurrence of an overload of predetermined value in any one ofthe poles of the breaker, the current responsive bimetal element acts totrip the breaker mechanism after a predetermined time interval. Ii theoverload in the circuit of any one of the poles is greater than apredetermined magnitude or is a short circuit, the electromagneticallyresponsive element in that pole acts to immediately trip the operatingmechanism and open all the circuit breaker contacts substantiallyinstantaneously. Suitable means are provided to restore all the parts ofthe trip device to operative condition following an operation.

The latch II9 (Figs. 3, d, 5, 6 and 7) is provided to prevent theovercenter spring 99 from closing the switch member I I until theoperating handle has reached a predetermined point during the closingoperation, that is, until the operating handle has been moved almost tothe fully closed position so that the operating spring will be stretchedsubstantially to the maximum length before the latch releases the switchmember II. This insures that the contacts will be closed quickly andpositively. This latch comprises a pair of parallel members I I9 (seeFig. 8) pivotally mounted by means of a pin I2I on the frame 4I, and thelatch is biased in a clockwise direction by a spring |25 having one endanchored to the latch and the other fast to a pin projecting from theframe 4|. A roller |23 (Figs. 6 and 7) rotatably supported on a pin I2l1connecting the members |I9 is adapted t0 cooperate with the toggle pin93 when the breaker mechanism is in the open position. The projectingfree end |26 of the latch I|9 engages the pin 93 of the toggle link 83to limit clockwise movement of the latch. The latch is released by theengagement of a shoulder |21 (Fig. 4) on the underside of the operatingmember 23 with a tail |28 of the latch II9.

Another latch comprising a bifurcated member |29 is also pivoted on thestud I2I. The purpose of this latch is to prevent the spring 99 frompartially closing the switch member II and thus prevent any rebound ofthe contacts from the open position in the event vthat the handle 25 isheld in the closed position when the breaker mechanism is tripped openby an overload current. The latch |29 is biased in a counter-clockwisedirection toward latching position by a spring Iiil (see Fig. 8) havingone end anchored on a pin |33 on the latch and the other end secured toa pin on the frame 4|. A cam face |30 on the upper fork of the latch |29is adapted to cooperate with the operating member 23 and the lower forkis shouldered as at |36 (Fig. Ll) to engage the toggle pin 93 in amanner to be more fully described later in connection With thedescription of the operation of the breaker.

When the breaker contacts ar-e in their fully closed position (Fig. 3)and an overload or short circuit occurs in the circuit controlled by anyone of the poles, the latch lever I I I is released by the trip devicel.. The latch lever III then moves counter-clockwise (Fig. 3) about itspivot I|5 under the influence of a spring |49 and also by a component ofthe force of the operating spring 99, one end of the spring |49 bearingon a projection I5I of the latch lever III. At this movement of thelatch lever, the yoke II2 thereof is moved out of restraining relationwith the yoke |08 of the carrier lever freeing the latter for movementby the operating spring 99 which, acting through the toggle link 84,immediately rocks the carrier lever |65 clockwise about its pivot |09.In this action, thc spring 99 is assisted by the contact springs 55 and66 acting through the switch members and the toggle 33-84, During theopening Operation, the line of action of the operating spring 99 movesfrom a position above the center of the pivot pin S9 for the operatingmember 23 to a position below the pin 80. This biases the operatingmember 23 in a clockwise direction about the pin Si) and immediatelymoves the operating member until it is Iarrested by engagement ofrollers |31 with the surfaces |39 on the carrier member |55. The partsare shown in this position in Fig. 4. This position of the operatinghandle provides a convenient means for indicating that the breaker hasbeen automatically tripped open.

When the parts are in their fully closed positions (Fig. 3) a smallclearance exists between a projection IM on the switch arm 'I6 (seen inFigs. 4, 5 and 6) and the yoke 92 of the toggle link 83. Soon after thelatch lever |II frees the carrier lever and the parts start theiropening movement, the contact members Il close this clearance and theprojection |41 comes into contact with the yoke 92. This causesclockwise movement of the knee pin 911 about the pivot pin 42 andchanges the line of action of the resultant force exerted by theoperating spring 99 so that the spring will tend to bias the knee or"the toggle inward toward collapsed position if the operating member 23is permitted to move to the intermediate position shown in Fig. 4. Whenthe toggle collapses, the parts are moved to the positions in which theyappear in Figure 4 in which the contacts are in the fully openedposition.

To effect manual opening of the contacts the operating handle 25 (Fig.3) is moved clockwise about the pivot 89. Shortly after the beginning ofthe clockwise movement, a projection |45 on the operating member 23engages the yoke $2 of the toggle link 83 and upon continued movement ofthe handle positively moves the toggle 83-84 in the direction to causecollapse. At the same time, the movement of the operating member 23moves the overcenter spring 99 across the center line of the toggle link84 whereupon it exerts a downward pull on the knee pin 94 causingcomplete collapse of the toggle. This causes the contacts to open with asnap action. The parts are shown in their manually opened position inFig. 5.

The latch ||9 (Figs. 3, 4, 5 and 6) is effective to latch the movableswitch members II in the open position whether the breaker is operatedmanually or tripped under the influence of an overload circuitcondition. As soon as the pivot pin 93 of the toggle link 83 passes tothe right of the roller |23 of the latch ||9, the spring |25 rocks thelatch clockwise into the path of the pin 93 to latch the movablecontacts in the open position. Y

Following each opening of the circuitbreaker in response to an overloadcircuit condition, itis necessary to restore the operating mechanism andthe trip device to an operative condition. This is accomplished bymoving the handle 25 from the position in which it is shown in Fig. 4 tothe full open position in which it appears in Fig. 5. During thismovement the rollers |31 on the operating member 23 engage the carrier|65 and move it counter-clockwise. As Vthe carrier |95 nears the end ofits counter-clockwise travel, the yoke |98 on the free end thereofengages a projection |55 (Fig. 3) forming a part of the yoke H2 of thelatch lever |H and rocks this lever clockwise. Near the end of theclockwise movement of the latch lever the latch element H1 thereofreengages the latch H4 of the trip device 1 and at the same time thelatch yoke H2 resumes its latching position in the path of the yoke 198.

When the breaker mechanism is in the open and reset position shown inFig. 5, the line of action of the spring 99 is below the center line91E-|91 and as a result the spring 99 restrains the toggle 83-85 in itscollapsed position (Figs. 4 and 5), the clockwise or opening movement ofthe movable contact assemblage being limited by the central clamp member45 striking thil frame 4|. In this position there is a slight clearancebetween the toggle pin 93 and the roller |23 of the latch l I9.

To close the circuit breaker the handle is rocked counter-clockwise tothe closed positionthe pin 93 and the latch roller |23, and since thelatch H9 occupies a latching position in the path of the toggle pin 93the movable contacts are held in the open position while thecounterclockwise movement of the operating member 23 increases thetension of the spring 99. Near the end of the counter-clockwise travelof the handle 25, the shoulder |21 on the operating member 23 strikesthe tail |23 and rocks the latch I9 counter-clockwise out of the path ofthe pin 93 Vwhereupon the spring 99 acts to straighten the toggle{i3-39, thus closing the contacts with a snap action.

When the contacts have been opened manually the latch H has not beentripped and the handle 25 occupies the position shown in Fig. 5. In thiscase the contacts may be closed by moving the handle 25 from theposition in Fig. 5 to that shown in Fig. 3. The latch H9 functions inthe above described manner to retain the parts in the open po-sition andto release the movable contact means near the end of the closingmovement of the handle 25.

Should an attempt be made to close the breaker against an overload or ashort circuit condition, the latch lever will again be released in theabove described manner, after a predetermined time delay orinstantaneously, depending on the magnitude of the overload current. Thecarrier lever |95 will also be released and will cause the mechanism toagain break the toggle 83-84 and open the contacts. It is not possible,therefore, to hold the breaker against an overload circuit condition.

When the operating mechanism 23 is in the A, closed position, thepreviously mentioned cam Cil -face |39 of the latch |29 is disposedjustbelow-a recess |35 in the operating member'23 and is heldinfunlatched position by the toggle pin 93 in the fork of the latch.When the lbreaker is opened either manually or automatically, the pin 93is withdrawn from the fork of the latch |29 to the position shown inFigs. 4 and 5. At the same time, the clockwise movement of the operatingmember 23 has moved the recess |35 toward the right from above the camface |30, and a projection |68 on the underside of the member 23 holdsthe latch |29 in its lower or ineiective position.

At the beginning of the counter-clockwise or closing movement of theoperating member 23, the toggle pin 93, under the influence of thespring 99 moves toward the left into contact with the roller |23 on thelatch H9 where it is restrained until near the end of the manual closingoperation of the operating member when the shoulder |21 strikes the tail|28 and disengages the latch H9. Since the shouldered portion |35 of thelatch l|29 is longer than the latch H9, it can -be seen that the latch|29 will be held out of the path of the pin 93 and will not be electiveto restrain the operating mechanism on normal operations.

Referring now to Fig. 6, if the breaker should be automatically trippedwhile the handle 25 and the operating member 23 are held in the closedposition, the latch l I9, due to the engagement of the shoulder |21 withthe tail |28, is held in its ineffective or unlatched position. However,as soon as the toggle 33-84 collapses and moves the toggle pin 93 clearof the shoulder |36, the latch spring |3| rocks the latch |29counter-clockwise interposing the shoulder |36 in the path of the togglepin 93, thus preventing rebound of the contact arm 16 from the openposition toward closed position. At this movement of the latch |29, thecam portion |30 enters the recess |35. Without the latch 29 the spring99 would tend to move the contacts towards closed position should thehandle be held in closed position when the breaker trips, as can be seenin Fig. 6 since in this position the line of action of the spring isabove the pivot |91.

The parts will remain in the position shown in Fig. 6 until the handleis released and moves clockwise to its Fig. 4 position. During the earlypart of the clockwise movement of the handle the shoulder |21 on theoperating member 23 moves away from the tail |28, permitting the spring|25 to rock the latch H9 into the path of the toggle pin 93. Slightlylater in the clockwise movement of the handle, the projection |48engages the cam portion |39 and rocks the latch 29 clockwise, moving theshoulder |36 out of the path of the toggle pin 93.

Y The manual clockwise movement of the handle 25 from its Fig. 4position to its Fig. 5 position resets the operating mechanism andreengages the latch member H1 with the trip device as previouslydescribed. The handle 25 is then moved counter-clockwise to its closedposition, the shoulder |21, near the end of its travel, rocking thelatch H9 to permit the spring 99 to reclose the contacts. Y

Should the handle 25 be moved from the tripped open position (Fig. 4) tothe closed position (Fig. 3) without first moving the handle to the openposition (Fig. 5) to reset the mechanism, the latch |9 would be moved toits unlatched position when the shoulder |21 strikes the'tail |28 of thelatch. The latch |29 is ineffective to restrain the contacts in openposition until the handle is near its closed position, consequently thecontacts will be moved to partly closed position since the center ofaction of the spring 39 is moved about the center line 94-1 01 uponmovement of the handle tc closed position.

In order to prevent this partial closing of the contacts by improperoperation of the handle, a modified form of the invention comprising alatch |53 (Fig. 9) is provided in place of the latch |29 of the originalembodiment. The latch is pivoted on the pivot l 2| and a spring |5'1urges the latch |53 in a counter-clockwise direction about its pivot tol-atching position. With the contacts and the operating handle in theclosed circuit position the latch |53 is restrained in its ineffectiveposition by the toggle pin 93, which thus assumes a position above thelatch at a point indicated at |51 (Fig. 9). When the breaker isautomatically tripped in response to an overload current in one of thepoles, the toggle collapses as previously described and the pin 93 movesto the position in which it is shown in Fig. 9. As the pin clears theshoulder of the latch |53, the spring |54 rocks said latchcounter-clockwise to the latching position shown wherein it is effectiveto prevent movement of the movable contact assemblage toward closedposition.

Since the latch |53 is not under the direct control of the handle 25 andthe operating member 23, movement of these parts to closed position willnot displace the latch |53 from its effective position. When the handle25 and the operating member 23 are moved to the open position (Fig. toreset the mechanism, the carrier |05 is rocked counter-clockwise to theposition shown in Fig. 5, moving the toggle 83-84 to its completelycollapsed position. At this movement the toggle link 33 rocks clockwiseabout the pin 93 from the position shown in Fig. 9 to that in which itappears in Fig. 5. During this movement a member |56 (Fig. 9) secured tothe inner face of the yoke S2 of the toggle link 83 engages a projection|59 on the latch |53 and rocks the latch clockwise to its ineffective orunlatched position. When the operating member 23 is now moved to theclosed position to close the contacts, the spring 99 moves above thecenter line S34-|31 and attempts to straighten the toggle 233-84. Sincethe latch ||9 at this time is in its latching position the movement ofthe toggle will be arrested by the pin 93 striking the roller |23.During the first part of the closing movement of the handle, the spring99 moves the toggle `a slight distance to take up the clearance betweenthe pin 93 and the latch I I9, and since the latch |53 is longer thanthe latch H3 the pin 93 passes above the latch |53 onto the surface |51thereof so that the latter is held in its unlatched position and doesnot now prevent closing the breaker. The movable contacts will bereleased for closinT movement by the spring 59 as previously disclosed,by the shoulder i2? moving the latch H9 to rits ineffective position asthe operating member 23 approaches its closed position. The spring 33then closes the contacts as previously set forth.

From the above description it is clear that the latch |53 of themodification has the additional function of holding the movable contactsin full open position until the handle has been properly operated toreset and reclose the breaker.

Having disclosed several embodiments of the invention in accordance withthe patent statutes, it is to be understood that various changes andmodifications may be made in the structural details disclosed withoutdeparting from some of the essential features of the invention. It is,therefore, desired that the invention be interpreted as broadly as theprior art permits, and that it is limited only by what is expresslystated in the following claims.

We claim as our invention:

l. A circuit breaker comprising relatively movable contacts, operatingmechanism therefor including an operating member movable to open and toclose said contacts, a member movable in response to predeterminedabnormal conditions in the circuit to cause automatic opening of thecontacts irrespective of the position of said operating member, saidmechanism being resettable following automatic opening of said contacts,and latch means pivoted on a fixed support and operable to lock saidcontacts open upon automatic opening thereof while the operating memberis held in closed position and until after said mechanism has beenreset.

2. A circuit breaker comprising relatively movable contacts, operatingmechanism therefor including an operating member movable to open and toclose the contacts, means releasable to cause automatic opening of thecontacts, said means being resettable by a predetermined movement of theoperating member, and latch means pivoted on a fixed support andoperable to lock the contacts open upon automatic opening thereof whilethe operating member is held in closed position and until after themechanism has been reset.

3. A circuit breaker comprising relatively movable contacts, aresettable operating mechanism therefor including an operating membermovable to open and to close the contacts, an operating toggle, anovercenter spring connecting said operating member and said toggle,means supporting one end of the toggle and release-bly to causeautomatic opening of the contacts, and latch means pivoted on a fixedsupport and operable to engage a part of said toggle to lock thecontacts open upon automatic opening thereof while the operating memberis held in closed position and until after the mechanism has been reset.

4. A circuit breaker comprising relatively movable contacts, operatingmechanism therefor including an operating member movable to open and toclose the contacts, a member movable in response to predeterminedabnormal conditions in the circuit to cause automatic opening of thecontacts irrespective of the position of said operating member, saidmechanism being resettable following automatic opening of the contacts,latch means pivoted on a fixed support and operable to lock the contactsopen upon automatic opening thereof while the operating member is heldin closed position and until after the mechanism has been reset, andanother latch means operable to lock the contacts open upon openingthereof and until the operating member is moved a predetermined distancein a closing direction.

5. A circuit breaker comprising relatively movable contacts, operatingmechanism therefor including an operating member movable to causeopening or closing of said contacts and including a member movable fromone position to a second position in response to predeterminedconditions to cause automatic opening of the contacts irrespective cfthe position of the operating member, said mechanism being resettable bya predetermined movement of said operating member following automaticopening of said contacts, means mounted for movement independently ofsaid mechanismandengageable with a part movable with the Ycontacts forautomatically locking said contacts in open position upon automaticopeninglthereof while the operating member is held in closed position,and until said mechanism has been reset. Y

6. A circuit breaker comprising relatively movable contacts, operatingmechanism therefor including anA operating member movable to open andclosed positions to cause opening and closing ofthe contacts, a membermovable from one position toV a second position in response topredetermined conditions to cause automatic opening of the contactsirrespective of the position of the operating member, and means mountedfor movement independently of said mechanism and engageable With a partmovable with the contacts for locking said contacts open upon automaticopening'thereof while the operating member is held in closed positionand until the operating member is moved a predetermined amount towardopen position.

71 'A circuit breaker comprising relatively movable contacts, operatingmechanism therefor ins Aof the contacts, a member movable from oneposition to a second position in response to predetermined condition tocause automatic opening ofthe contacts irrespective of the position ofthe operating lmember, and means mounted for movement independently ofsaid mechanism and engageable with a part movable with the contacts forlocking the contacts open upon automatic opening thereof While saidYoperating member is held in closed position and until the operatingmember is moved to its full open position.

8. A' circuit breaker comprising relatively movable contacts, operatingmechanism therefor including an operating member movable to open andclosed positions to cause opening and closing ofthe contacts,.a membermovablefrom one position to a second position in response topredetermined conditions to cause automatic openingof the contactsirrespective'of the position of the'operating member, and means mountedfor movement independently of said mechanism and engageable with a partmovable with the contacts for locking said contacts in open positionupon automatic opening of said contacts as long as the operating memberis within -a predetermined distance of the closed position.

9. Acircuit breaker comprising relatively movable contacts, operatingmechanism therefor including an operating member movable to open andclose Vthe contacts, a. member movable in response to predeterminedabnormal conditions in theicircuit to cause automatic opening of thecontacts irrespective of the position of said operating member, saidmechanism being resettable by a predetermined movement of said operatingmember after automatic opening of said contacts,v

and a pair of coaXially pivoted latch members engageable with a partmovable with the movable contacts, one of said latch members beingoperable to automatically lock the contacts open upon automatic openingthereof and until said operating member is moved a predetermined amountin an opening direction, the other of said latch members being operableto lock the contactsl open upon automatic opening thereof until theoperating member is moved a predetermined distance in a closingdirection.

l0. A circuit breaker comprisingV relatively movable contacts, operatingmechanism therefor including an operating member movable to causeopening or closing of said contacts and including a member movable fromone position to a second position in response to predeterminedconditions to cause automatic opening of said contacts, and a latchmovable independently of said mechanism and engageable with a partmovable with the contacts for automatically locking said contacts infull open position upon automatic opening thereof, said latch beingeiective to lock said contacts open as long as said operating memberremains in closed position or in proximity to closedposition afterautomatic opening of said contacts.V

1l. lA circuit breaker comprising relatively movable contacts, operatingmechanism therefor including an operating handle movable to an openposition and to a closed position to open and close said contacts, and amember movable in response to predetermined abnormal circuit conditionsto cause automatic opening of the contacts irrespective of the positionof the operating handle, said operating mechanism being resettablefollowingl automatic opening of the contacts, and latch means pivoted ona xed support and operable to lock said contacts open upon automaticoperation thereof while the handle is held in closed position.

i2. A circuit breaker comprising relatively movable contacts, operatingmechanism for said contacts including an operating handle movable toopen and closed positions to cause opening and closing of the contacts,a member movable from one position to a second position in response topredetermined conditions to cause automatic opening of the contactsirrespective of the position of the operating handle, and means mountedfor movement independently of said mechanism and engageable with a partmovable with the contacts for locking the contacts open upon automaticopening thereof While the handle is held in closed position. TURELINDSTROM. JEROME SANDIN.

